diff --git a/libraries/plugins/auth/AuthenticationCookie.class.php b/libraries/plugins/auth/AuthenticationCookie.class.php
index d0ac972b8c..1d35b139ff 100644
--- a/libraries/plugins/auth/AuthenticationCookie.class.php
+++ b/libraries/plugins/auth/AuthenticationCookie.class.php
@@ -413,14 +413,14 @@ class AuthenticationCookie extends AuthenticationPlugin
 
         // Ensures valid authentication mode, 'only_db', bookmark database and
         // table names and relation table name are used
-        if ($cfg['Server']['user'] != $GLOBALS['PHP_AUTH_USER']) {
+        if (! hash_equals($cfg['Server']['user'], $GLOBALS['PHP_AUTH_USER'])) {
             foreach ($cfg['Servers'] as $idx => $current) {
                 if ($current['host'] == $cfg['Server']['host']
                     && $current['port'] == $cfg['Server']['port']
                     && $current['socket'] == $cfg['Server']['socket']
                     && $current['ssl'] == $cfg['Server']['ssl']
                     && $current['connect_type'] == $cfg['Server']['connect_type']
-                    && $current['user'] == $GLOBALS['PHP_AUTH_USER']
+                    && hash_equals($current['user'], $GLOBALS['PHP_AUTH_USER'])
                 ) {
                     $GLOBALS['server'] = $idx;
                     $cfg['Server']     = $current;
diff --git a/libraries/plugins/auth/AuthenticationHttp.class.php b/libraries/plugins/auth/AuthenticationHttp.class.php
index 54a49ad09c..ad695e3510 100644
--- a/libraries/plugins/auth/AuthenticationHttp.class.php
+++ b/libraries/plugins/auth/AuthenticationHttp.class.php
@@ -164,7 +164,7 @@ class AuthenticationHttp extends AuthenticationPlugin
         // User logged out -> ensure the new username is not the same
         $old_usr = isset($_REQUEST['old_usr']) ? $_REQUEST['old_usr'] : '';
         if (! empty($old_usr)
-            && (isset($PHP_AUTH_USER) && $old_usr == $PHP_AUTH_USER)
+            && (isset($PHP_AUTH_USER) && hash_equals($old_usr, $PHP_AUTH_USER))
         ) {
             $PHP_AUTH_USER = '';
             // -> delete user's choices that were stored in session
@@ -197,12 +197,12 @@ class AuthenticationHttp extends AuthenticationPlugin
 
         // Ensures valid authentication mode, 'only_db', bookmark database and
         // table names and relation table name are used
-        if ($cfg['Server']['user'] != $PHP_AUTH_USER) {
+        if (! hash_equals($cfg['Server']['user'], $PHP_AUTH_USER)) {
             $servers_cnt = count($cfg['Servers']);
             for ($i = 1; $i <= $servers_cnt; $i++) {
                 if (isset($cfg['Servers'][$i])
                     && ($cfg['Servers'][$i]['host'] == $cfg['Server']['host']
-                    && $cfg['Servers'][$i]['user'] == $PHP_AUTH_USER)
+                    && hash_equals($cfg['Servers'][$i]['user'], $PHP_AUTH_USER))
                 ) {
                     $server        = $i;
                     $cfg['Server'] = $cfg['Servers'][$i];